Yup. Anti-matter has positive mass. And only a 100 mile radius? The explosive energy, assuming the subject weighs a mere 60 kilograms, would be as much as 200,000 Hiroshima bombings. Not everything in a 100 mile radius, but everything on the ENTIRE PLANET would be severely endangered.

It would still have been 4000 times as weak as the Dinosaur-extinction meteor impact, though.